In the desire to reduce noise emitted from internal combustion engines oil pans, various sound dampening arrangements have been proposed. U.S. Pat. No. 4,851,271, discloses a laminated oil pan structure of a thin plastic damping material positioned between flat inner surfaces of the pan and stamped steel insert pan liners.
An engine sound deadening arrangement is disclosed in U.S. Pat. No. 3,991,735, which provides a liquid sound barrier in the form of an oil reservoir between a cylinder block walls and cowling cover.
The Society of Automotive Engineers, Inc. paper No. 1999-01-1759, entitled: "Development of a Technique for Using Oil Viscosity to Reduce Noise Radiated from the Oil Pan", discloses a vibration dampening technique for engine oil pans to reduce radiation noise. Damping is obtained with a "squeeze" oil pan, formed with a thin oil film between the pan and an added inner plate, which reduces the pan vibration level to lower radiation noise.